Differential fluid pressure motor



Aug. 31, 1 954 w. E. O'SHEI 2,687,707 DIFFERENTIAL FLUID PRESSURE MOTOR Filed July 14, 1952 Patented Aug. 31, 1954 UNITED STATES PATENT OFFICE 2,687,707 DIFFERENTIAL FLUID PljESSURE MOTOR William Edward OShei, London, England Application July The present invention relates to a silencing device for suction motors, and more particularly for suction motors as used for driving windscreen wipers. An object of the invention is to provide an arrangement for reducing the noise caused by the atmospheric air being sucked intothe motor.

Such motors are normally oscillating piston or paddle connected to drive a rocker shaft which operates an automatic valve mechanism for alternately applying suction to opposite ends of the motor whilst simultaneously venting the other end of the motor. The automatic valve mechanism is normally arranged in a valve chamber provided with a detachable cover, atmospheric air being admitted to the valve chamber through one or more apertures in the cover. In order to reduce the noise caused by air being sucked through these apertures, they have been covered with a layer of felt or like sounddeadening material. This has impaired the emciency of the motor by reason of the factthat, after the motor has been in use for some time, the pores of the felt become clogged with particles of dust. The felt thus also acts as a dust filter and has to be replaced fromtime to time.

According to the present invention, air is adthrough a self-opening valve material, the valve opening to depending upon the operation of flexible different amounts of the motor. combination with a suction operated motor, controlled by an automatic valve arranged in a valve chamber, to which atmospheric air is admitted and from which the air is sucked through ports controlled by the automatic valve, a silencingdevice for reducing the noise caused by the atmospheric air being sucked into the motor comprising a self-opening valve, through which the air is admitted to the valve chamber, said self-opening valve being formed of a flexible material having a slit therein which opens to difierent amounts depending upon the volume of air passing through the self-opening valve.

In order that the invention may be more fully understood, some embodiments thereof, given by Way of example, will now be described with reference to the accompanying drawings in which:

Fig. 1 shows a perspective view of a differential fluid pressure motor, with the cover of the automatic valve chamber removed and incorporating a self-opening valve according to the invention;

Fig. 2 shows a section on a larger scale along the line X-X in Fig. 1;

constructed with an s The invention also provides in A 14, 1952, Serial No. 298,736 9 Claims. (Cl. 121142) Fig. 4 shows a fragmentary view of an alternate construction of self-opening valve.

fluid pressure motor of the oscillating paddle type in which the piston or paddle, indicated in dotted lines at I, is adapted to move within an arcuate paddle chamber forming the Fig. 3 shows a rear view of the self-opening valve in Figs. 1 and 2; and

motor casing 2, so that the paddle drives a rocker shaft 3, to one end of which is a windscreen wiper or the like may be connected. Associated with the other end of the rocker shaft 3 is an automatic valve generally indicated at 4 and housed within a valve chamber 5 carried by the motor casing. This automatic valve is adapted to be actuated in response to the movement of the piston I to connect a suction port alternately to either one of two other ports through which. suction is applied, to cause the piston l to reciprocate. The other port which is not connected at any instant tothe suction is open to the space within the valve chamber 5. Atmospheric air is admitted to the valve chamber aperture 6, provided in the detachable cover 7 of the valve chamber. This cover is normally secured to the valve chamber 5, for example by means of screws 8 engaging in threaded bores 9 provided on the valve chamber 5. The motor casing 2, valve chamber 5 and cover 1 are preferably made of metal and may be alloy die-castings. According to the invention, the aperture 6 in the cover I is fitted with a member It] of rubber-like material having a small slit H cut therein so as to form a self-opening valve member.

As shown more clearly in Fig. 2, the member I!) preferably comprises a rubber disc which may be dish-shaped so that it fits Within the circular aperture 6, with the edge of the rubber disc :accommodated in an annular seating i2 surrounding the circular aperture. A metal washer I3 is positioned over the back of the rubber disc, and the disc and the washer are together held in position by spreading portions of the metal surrounding the aperture over the edge of the washer as shown at 14. To facilitate this spreading of the metal, a raised lip I5 is provided surrounding the seating l2 and pressure is applied to portions of this lip to spread the metal over the edge of the washer.

Fig. 3 shows three such Spread portions l4 formed in the metal lipl5. The slit II is normally closed by reason of the resilient nature of the rubber member, but is opened to different extents by the quantity of air flowing therethrough a circular through. Any tendency of the valve to become sealed by dust is avoided and if dust collects on the valve, the valve can simply open to a larger extent. The valve member is preferably formed from rubber sheet, having a thickness of about .020".

As shown inFig. l, according to a modification of the invention, the member It of rubber-like material may be formed with a slit !8 of minimum Width so as to remain permanently open, but being more fully opened by the air flowing through the valve. The self-opening valve may be constructed of any flexible material, such as leather or rexine, although a valve constructed from natural or synthetic rubber is preferred.

Furthermore, it will be understood that the valve chamber may be mounted remote from the motor and the automatic valve be connected to the motor for operation in response to the movement of the piston or the like, through a linkage mechanism.

I claim:

1. In combination, a suction operated motor, and a silencing device for reducing the noise caused by the atmospheric air being sucked into the motor, said silencing device comprising a self-opening valve formed of flexible material through which the air sucked into the motor passes, the valve opening to difierent amounts depending upon the operation of the motor.

2. In combination, a suction operated motor, a valve chamber, an automatic valve for controlling the admission of atmospheric air to the motor arranged in said valve chamber, and a silencing device for reducing the noise caused by the atmospheric air being sucked into the motor, said silencing devic comprising a self-opening valve through which air is admitted tothe valve chamber, said self-opening valve comprising a member of flexible material and a slit formed in said member of flexible material, said slit opening to different amounts depending upon the operation of the motor.

3. For controlling the operation of a suctionoperated motor, a valve chamber, an automatic valve housed within said valve chamber for alternately applying suction to opposite ends of the motor whilst simultaneously venting the other end of the motor to the atmosphere, a silencing device through which air is admitted to the valve chamber, said silencing device comprising a member of flexible material and a slit formed in the member of flexible material, said slit opening to different amounts depending upon the operation of the motor.

4:. Apparatus as claimed in claim 3, wherein the member of flexible material is made from a rubber material.

5. Apparatus as claimed in claim 3, wherein the slit is formed with a minimum width so as to remain permanently open, but being more fully opened by the air flowing through the valve.

6. Apparatus as claimed in claim 3, wherein the self-opening valve is formed in a detachable cover secured over the valve chamber.

'7. For controlling a suction-operated motor, an automatic valve assembly comprising a valve chamber, a suction inlet port, a first outlet port, a second outlet port, an automatic valve, means for moving said automatic valve to connect said suction inlet port, alternately to said first outlet port and to said second outlet port, that one of said first or second outlet ports which is not connected at any instant to the suction inlet port being open to the space within the valve chamber, said valve chamber being closed from the outer atmosphere except for a self-opening valve comprising a member of flexible material having a slit therein which opens to different amounts depending upon the volume of air passing into the valve chamber.

8. A suction-operated motor comprising a casing, an arcuate chamber within said casing, a paddle located in said arcuate chamber, a valve chamber, an automatic valve located within said valve chamber for alternately applying suction through said valve to opposite sides of the paddle while simultaneously venting the other side of the paddle to the atmosphere within the valve chamber, a rocker shaft connected to said paddle and to said automatic valve, means enclosing the valve chamber from the outer atmosphere, an aperture. in said enclosing means, and a selfopening valve located in said aperture through which air is admitted to the valve chamber, said self-opening valve comprising a member of flexible material and a slit formed in said member of flexible material said slit opening to difierent amounts depending upon the volume of air passing into the valve chamber.

9. Apparatus as claimed in claim 8, wherein the member of flexible material is made from a rubber material.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,102,824 White Dec. 21, 1937 2,138,605 Landis Nov. 29, 1938 2,322,631

Groeniger June 22, 1943 

